Abstract
Global cerebral ischemia is a cerebrovascular disease caused by cardiac arrest or cardiac surgery. Chronic and excessive neuroinflammation is a major contributor to cell death in the pathophysiology of global ischemia, likely having a detrimental effect on cognitive function. Bromodomain-containing protein 4 (BRD4) plays a pivotal role in the transcriptional regulation of inflammation in this event. Therefore, inhibiting BRD4 may be a novel therapeutic strategy for decreasing neuroinflammation and delaying cognitive deficits. RNAi technology has the potential to overcome the limitations of current therapies. siRNA can specifically degrade the BRD4 mRNA, consequently suppressing the BRD4 expression, thereby protecting neurons from neuroinflammation. However, the blood-brain barrier (BBB) causes a significant challenge in delivering siRNA to the brain. To address this issue and suppress BRD4, this study developed PLGA nanoparticles coated with Polysorbate-80 (PS-80) and Polyethylene glycol (PEG) to incorporate siRNA and effectively deliver across the BBB.
The study engineered siRNA-incorporated PLGA nanoparticles with PS-80 and PEG coating via a modified nanoprecipitation method. The nanoparticles were characterized for their particle size, zeta potential, polydispersity, and encapsulation efficiency. A detection technique to validate surface modification achieved via PEGylation was established using UV spectroscopy. Furthermore, in vitro tests revealed that lower concentrations of nanoparticles have less toxicity to N2A cells than higher concentrations of blank nanoparticles. Higher permeability of PEG+PS-80 coated nanoparticles was observed, suggesting their potential as a delivery system to cross the BBB and deliver siRNA. Cellular uptake studies revealed a higher uptake of PEG+PS-80 coated nanoparticles in N2A cells.
Additionally, the nanoparticles showed low hemolysis and protein adsorption, indicating their suitability for intravenous administration. Moreover, in vivo studies demonstrated that these surface-modified nanoparticles have a significantly higher uptake in the hippocampal CA1 region, implicating their potential to be taken up by the neuronal cells and surrounding brain tissue.
In conclusion, this study developed a novel delivery system for siRNA using PEG and PS-80 surface modifications on PLGA nanoparticles. These nanoparticles were characterized and evaluated for their safety and efficacy profiles, highlighting their potential as stable delivery vehicles for siRNA.